AT93C46_07 Datasheet, PDF (5/18 Pages) ATMEL Corporation – Three-wire Serial EEPROM

AT93C46
Table 5. Instruction Set for the AT93C46
Instruction SB
Op
Code
Address
x8
x 16
READ
1
10
A₆ – A₀
A₅ – A₀
EWEN
ERASE
WRITE
ERAL
1
00
11XXXXX 11XXXX
1
11
1
01
A₆ – A₀
A₆ – A₀
A₅ – A₀
A₅ – A₀
1
00
10XXXXX 10XXXX
Data
x8
x 16
D₇ – D₀
D₁₅ – D₀
WRAL
1
00
01XXXXX 01XXXX
D₇ – D₀
D₁₅ – D₀
EWDS
1
00
00XXXXX 00XXXX
Note: The Xs in the address field represent DON’T CARE values and must be clocked.
Comments
Reads data stored in memory, at
specified address
Write enable must precede all
programming modes
Erases memory location A_n – A₀
Writes memory location A_n – A₀
Erases all memory locations. Valid
only at V_CC = 4.5V to 5.5V
Writes all memory locations. Valid
only at V_CC = 4.5V to 5.5V
Disables all programming instructions
Functional
Description
5140B–SEEPR–2/07
The AT93C46 is accessed via a simple and versatile three-wire serial communication
interface. Device operation is controlled by seven instructions issued by the host pro-
cessor. A valid instruction starts with a rising edge of CS and consists of a start bit (logic
“1”) followed by the appropriate op code and the desired memory address location.
READ (READ): The Read (READ) instruction contains the address code for the mem-
ory location to be read. After the instruction and address are decoded, data from the
selected memory location is available at the serial output pin DO. Output data changes
are synchronized with the rising edges of serial clock SK. It should be noted that a
dummy bit (logic “0”) precedes the 8- or 16-bit data output string.
ERASE/WRITE ENABLE (EWEN): To assure data integrity, the part automatically goes
into the Erase/Write Disable (EWDS) state when power is first applied. An Erase/Write
Enable (EWEN) instruction must be executed first before any programming instructions
can be carried out. Please note that once in the EWEN state, programming remains
enabled until an EWDS instruction is executed or V_CC power is removed from the part.
ERASE (ERASE): The Erase (ERASE) instruction programs all bits in the specified
memory location to the logical “1” state. The self-timed erase cycle starts once the
Erase instruction and address are decoded. The DO pin outputs the Ready/Busy status
of the part if CS is brought high after being kept low for a minimum of 250 ns (t_CS). A
logic “1” at pin DO indicates that the selected memory location has been erased and the
part is ready for another instruction.
WRITE (WRITE): The Write (WRITE) instruction contains the 8 or 16 bits of data to be
written into the specified memory location. The self-timed programming cycle t_WP starts
after the last bit of data is received at serial data input pin DI. The DO pin outputs the
Read/Busy status of the part if CS is brought high after being kept low for a minimum of
250 ns (t_CS). A logic “0” at DO indicates that programming is still in progress. A logic “1”
indicates that the memory location at the specified address has been written with the
data pattern contained in the instruction and the part is ready for further instructions. A
Ready/Busy status cannot be obtained if the CS is brought high after the end of the self-
timed programming cycle tWP.
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